Buffers with combination fluid accumulator and seal means



April 22, 1969 G. w. KAMMAN BUFFERS WITH COMBINATION FLUID ACCUMULATOR AND SEAL MEANS Sheet of2 Filed June 8. 1966 J INVENTOR. ordozz W ATTORNEYS April 22, 1969 G. W. KAMMAN BUFFERS WITH COMBINATION FLUID ACCUMULATOR AND SEAL MEANS Sheet 3 of2 Filed June 8, 1966 \v hm \\N Mm NM %m \m mm 4 7 a if; WE Wm Q L Mm \3 mm a N8 KN NQN NN N m m X A mww I \\N NM p \N M\ W w/ W %\N g s l n \m Wm m m x E w v H 7 A. MN W N\ \v W 3 mm w a kw mm a \n W h (A/w/ MW. \NW 1/ MW mv wh hm.

INVENTOR.

al @34 @yWJT/TORNEYS United States Patent 3,439,913 BUFFERS WITH COMBINATION FLUID ACCUMULATOR AND SEAL MEANS Gordon W. Kamman, Buffalo, N.Y., assignor to Houdaille Industries, Inc, Bulfalo, N.Y., a corporation of Michigan Filed June 8, 1966, Ser. No. 556,188

Int. Cl. B60g 11/26; F16f /00, 13/00 U.S. Cl. 267-65 12 Claims ABSTRACT OF THE DISCLOSURE Hydraulic buffers comprise a tubular housing having opposite end closures defining a cylindrical working chamber, metering means extending from one of the closures in the chamber, a plunger coactive with the metering means and extending from the other closure, a coiled expansile compression spring normally biasing the plunger into protracted relation, and a combination fluid sealing and accumulator flexible sleeve above the plunger and spring and having a small diameter end secured sealingly to the plunger and a larger diameter end sealingly secured to the housing. A clamping ring securing the smaller end of the sleeve to the plunger serves also as a bumper stop for the plunger.

This invention relates to hydraulic buffers and more particularly concerns buffers of the type in which a plunger coacts with metering means in hydraulic fluid in a bufling chamber.

A distinct problem in buifers which must operate through a great many cycles in service resides in the wearing of the customary seals between the plunger and the end closure of the buffer housing through which the plunger reciprocates. -O-rings and other types of ring seals may serve satisfactorily where in the operating life of the buifer a relatively few thousand buffing cycles are encountered. There are, however, types of buffers employed on machinery, oflice equipment, and in other continuously or substantially continuously cycling apparatus in which the butter seals should withstand into the millions of working cycles.

Accordingly, it is an important object of the present invention to provide a novel hydraulic buffer construction in which leakage is virtually eliminated throughout a prolonged cyclic life of the unit.

Another object of the invention is to provide a new buffer construction in which all problems of seal friction and abrasive wear are eliminated.

Still another object of the invention is to provide a new buffer construction having a novel combination fluid accumulator and seal structure.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a longitudinal diametrical sectional detail view through a buffer construction embodying features of the invention;

FIGURE 2 is a fragmentary sectional view of the buffer of FIGURE 1 showing the relationship of parts at the termination of a buffing stroke;

FIGURE 3 is a longitudinal sectional view through a modified form of the buffer;

FIGURE 4 is a fragmentary sectional view of the buffer of FIGURE 3 showing the same at termination of a bufiipg stroke;

FIGURE 5 is a longitudinal sectional view through another modified form of the butfer; and

FIGURE 6 is a fragmentary longitudinal sectional view "ice of the buffer of FIGURE 5 showing the same at termination of a buffing stroke.

With reference to FIGURES 1 and 2, a buffer 10 according to the present invention includes a one-piece tubular housing 1.1 defining a chamber 12 of substantial diameter therein and having on one end a joint-free end closure 13 while the opposite end has an opening 14 closed by an end closure 15 secured therein in any preferred manner. Means are desirably provided for securing the head end of the buffer provided by the end closure :13 to a support in apparatus with which the buffer is used, such means herein comprising an integral axial attachment head stem boss projection 17 which is externally threaded for attachment purposes. For filling hydraulic fluid into the chamber 12, the head projection 17 has an axial passage bore 18 therethrough and opening through the end closure 13 into the chamber. After cfilling the opening 18 is closed as by means of a tapered threaded plug 19.

Bufling is effected within the chamber 12 in the pres ence of the hydraulic fluid by coaction of a metering tube 20 and a relatively reciprocably slidably related plunger 21. In this instance, the metering tube is mounted coaxially within the chamber 12 in a head flange block 22 fitting in the joint-free end of the chamber 12 defined by the housing, with a clearance recess 23 opening toward the filling opening 18 and an axial peripheral groove 24 effecting communication between the recess 23 and the chamber 12 for free movement of hydraulic fluid.

Slidable engagement of the plunger 21 with the metering tube 20 is about the outside perimeter of the tube, and the plunger is for this purpose provided with a blind end complementary bore 25 closed at the outer end of the plunger by an impact head 27 which is engageable by a member of apparatus with which the buffer is used and which acts to drive the plunger in a bufling stroke inwardly through an axial opening 28 in the end closure member 15 affording a free reciprocation guide for the plunger. Normally the plunger is biased into a protracted relation by means of a compression spring 29 seated at one end against the inner side of the buffer head 27 and at its opposite end thrusting against a retaining spider disc 30 seating against the mounting block 22 within the mounted end of the metering tube 20 and retaining a ball check valve 31 within a cage bore 32 and in operative relation to a seat about a return stroke replenishing metering orifice 33 communicating with the recess 23. During inward buffing strokes of the plunger 21 hydraulic fluid which has been filled into the chamber defined within the metering tube 20 and the hollow plunger past the check valve 31, is displayed by the plunger through metering orifices 34 extending through the metering tube and disposed in a suitable buffing control pattern along the length of the normally uncovered portion of the metering tube to be progressively closed as the plunger progresses inwardly in the buffing stroke. During the buffing stroke the check valve 31 closes, but readily opens as the plunger returns under bias of the spring 29, to thereby avoid hydraulic lock, and also serving to meter the replenishing fluid for damping return stroke movement of the plunger.

In order to seal the buffer unit 10 against leakage of hydraulic fluid in a manner which eliminates any problem of wear on the sealing means due to relative reciprocal movements of the plunger and the end closure 15, and also to provide a reservoir accumulator space within the chamber 12, a resiliently flexible, fluidimpervious, combination sealing and accumulator sleeve 35 is mounted within the chamber 12 between the housing 11 and the plunger 21 and divides the chamber into hydraulic fiuid containing reservoir space about the metering tube 20 and the plunger and an air space opening to atmosphere past the plunger through the opening 28 in the end closure. In this instance, the sleeve 35 comprises a thin originally tapered elongated sleeve formed from suitable rubber material and retroverted with its smaller diameter end engaging the plunger 21 and its larger diameter end engaging the tubular housing 11.

A thorough liquid sealing securement of the smaller diameter end of the sleeve 35 through the plunger 21 is elfected by tensioned engagement of an anchoring head 37 integral on such end in an annular outwardly opening groove 38 in the perimeter of the plunger, and firmly clamping the head in the groove by means of a clamping ring 39 engaging about the bead. Location of the sleeve attachment and the securing ring 39 intermediately along the length of the plunger 21 is at a point which will permit full range of buffing and return stroke reciprocation of the plunger and wherein the clamping ring will serve as a fixed stop in engagement with the inner side of the closure to define the outermost protracted limit of the plunger under spring bias. Longitudinal displacement of the ring 39 on engagement with the end closure 15 is prevented by an annular lip flange 40 on the ring seating against the free end of the sleeve as defined by the securement or anchoring rib or head 37. Further, since the head 37 is of a resilient rubber material it serves as a bumper cushion for the clamping ring 39 when it acts as a stop and thrusts to a sudden halt against the closure 15.

At its opposite, larger diameter end, the sleeve 35 is positively secured sealingly to the housing 11, and provides a static joint seal between the housing and the end closure 15. For this purpose, the larger diameter end of the sleeve has a rib-like head 41 integral therewith and engaged under sealing compression against the opposing housing wall surface and within an outwardly opening annular groove 42 in the end closure 15.

As the plunger 21 is driven into the chamber 12 in a bufling stroke, fluid is displaced by the plunger from within the metering tube and there is also a certain amount of bulk displacement of fluid by the intruding plunger itself. To accommodate such fluid displacement, the flexible sleeve member 35 conveniently collapses away from the wall defining the chamber 12 and affords an accumulator space 43 as shown in FIGURE 2, with corresponding reduction in volume of an air space 44 which is isolated from the reservoir portion of the chamber and communicates through the bore 28 with atmosphere. When the plunger returns to its protracted position, the air space 44 refills through the passage of the bore 28 as the accumulator space evacuates.

In FIGURES 3 and 4 a buffer structure 45 is depicted which operates substantially the same as the butter 10 but differs therefrom in the form of the hydraulic fluid displacing plunger, the relationship of the return biasing spring to the plunger and the metering tube and in the specific construction of the combination accumulator and sealing tube. In this instance, the butter 45 comprises a tubular housing 47 defining a chamber 48 closed at one end by an integral joint-free end closure 49 provided with a central outwardly projecting externally threaded attachment boss 50 for connecting the unit to one of opposed relatively movable members between which the buffer is used. A central filler opening 51 through the stem or boss 50 and the closure 49 is closed by a plug 52 after filling the unit with hydraulic fluid.

At its opposite end the tubular housing 47 has an opening 53 closed by an end closure disc 54 having a central opening providing a freely slidable guide for a plunger 55 extending therethrough and adapted for engagement at its outer end by the other of opposed members between which the butter is used. In this instance the plunger 55 is of solid cylindrical construction and has an inner piston end portion 57 engaged for slidable bufling coaction within a metering tube 58 having .4 staggered sets of metering orifices59 and which is centrally mounted in a flange disc member 60 seated within the joint-free inner end portion of the chamber 48 against the end closure 49.

Filling of hydraulic fluid into the actuator through the filler opening 51 past the flange disc 60 is by way of a recess 61 in the face of the disc which opposes the filler opening. Communicating with this recess is a passage bore 62 which opens into the reservoir space outside the metering tube 58. In addition a filler and return stroke metering port or orifice 63 communicates with the bore of the metering tube 58 through its mounted end within which a spider 64 retains a ball check valve 65 within operating range of its seat at the inner end of the orifice 63 so that the orifice 63 opens for filling and during return strokes of the piston 57 and is closed against fluid passage during inward butfing strokes of the piston.

Normally the plunger 55 is biased into protracted, return stroke direction by means comprising a coiled compression spring 67 of slightly larger inside diameter than the metering tube 58 and concentrically disposed thereabout, with one end of the spring engaging against the disc 60 and the opposite end thrusting against a thrust washer 68 mounted on and about the plunger 55 adjacent to the outer end of the elongated cylindrical piston portion 57.

Enclosing the spring 67 in spaced relation, defining a reservoir and accumulator space within the chamber 48 and serving as an eflicient seal against escape of hydraulic fluid from the butter unit past the secured end closure 54 and more particularly through the plunger guide bore thereof, is an elongated resiliently flexible thin elastomeric or rubber sleeve 69 preferably cylindrical throughout the major extent of its length in its relaxed condition. At one end the sleeve 69 sealingly engages with the plunger 55, being for this purpose provided with a generally radially inwardly extending annular flange 70 having on its inner edge an enlarged annular sealing and anchoring rib head 71 which seats in an annular radially outwardly opening groove 72 provided at juncture of the piston portion 57 with the outer end portion of the plunger 55. At the axially outer side of the groove 72 it is defined by a thrust shoulder 73 facing axially inwardly and toward which the thrust washer 68 thrusts the head 71 sealingly. Radially outward stretching displacement of the head 71 from the groove 72 is precluded by a retainer ring 74 which engages within a reentrant groove 75 defined at juncture of the flange 70 with the bead 71 and facing generally radially and axially outwardly, with a second annular connecting neck 77 on the flange 70 serving as a cushion between the thrust washer 68 and the retaining ring 74, which latter also serves as a bumper stop engaging the closure 54 at the limit of outward protractional return movement of the plunger.

Sealing engagement of the opposite, innermost end of the sleeve 69 with the housing 47 and effected by means of a terminal rib head 78 which is joined to the body of the sleeve 69 by means of a radially outwardly and axially inwardly tapered flaring connecting annular flange 79. Sealing anchorage of the bead 78 is effected by engagement thereof under compression within an annular radially outwardly opening groove 80 formed in the perimeter of the disc member 60 and having a tapered lead-in annular surface 81 against which the flange 79 normally rests. Through this arrangement the sleeve 69 extends longitudinally intermediate and in spaced relation to the longitudinal wall defining the chamber 48 and to the spring 67. To facilitate assembling the disc member 60 axially into position with the sealing and anchoring means 78 engaged in the groove 80, the longitudinal wall of the chamber 48 beyond that portion engaged by the perimeter of the disc is of slightly larger diameter, with a tapered annular lead-in shoulder 82 joining the larger and reduced diameter portions of the wall to enable easing of the bead 78 into compressed sealing engagement with the housing.

Filling of the buffer 45 with hydraulic fluid is effected while the plunger 55 is in its protracted position and the sleeve 69 is relaxed, whereby the reservoir space defined within the sleeve and the metering tube 58 are filled with hydraulic fluid. When the filler opening 51 is then closed by means of the plug 52 the hydraulic fluid is completely sealed within the sleeve 69 against escape, and a substantial air space 83 is present within the chamber 48 about the sleeve 69. During an inward, bufling stroke of the plunger 55, the sealing sleeve 69 rollingly introverts with the plunger and stretches radially and axially as an accumulator to accommodate fluid displaced by the plunger as it moves inwardly in the metering tube 58, as shown in FIGURE 4. Uneven pressures against the sleeve 69 during the bufling stroke, and protection against sucking of the thin sleeve against the spring 67 or into the fluid displacement passage 62 or the metering orifices 59, is afforded by a rigid guard sleeve 84 mounted on the inner end of the disc 60 concentrically about the spring 67 opposite the length of the metering tube having the orifices 59.

A butter unit 85 as disclosed in FIGURES 5 and 6 comprises a somewhat simplified version of the buffer 10. To this end, the buffer 85 comprises a rigid one-piece tubular housing 87 having solidly in one piece therewith an end closure 88 provided with an externally threaded outwardly projecting central attachment boss 89. A filler port 90 through the boss 89 is closed after filling by a plug 91, with the inner end of the filler opening controlled by a ball check valve 92 within a valve chamber in an axially inwardly projecting integral boss 93 on the closure 88. Attached to the housing by engagement about the boss 93 is an elongated metering tube 94 having staggered metering orifices 95 and about which is coactively telescopically slidably engaged an elongated tubular piston plunger 97 having therein a chamber bore 98 closed integrally at the outer end of the plunger by an impact head 99 and providing on its inner side a thrust seat for a biasing compression spring 100 which at its inner end seats against a spider 101 thrusting against the inner end of the boss 93.

Providing a fluid seal, and accumulator and dividing a chamber 102 within the housing 87 into a reservoir space and an air space 103, is a thin resiliently flexible fluid-impervious sleeve 104 which is normally introverted with one longitudinal portion engaging about the portion 97 and an opposite longitudinal portion engaging the wall defining the chamber 102. Fluid sealing anchorage of the sleeve to the plunger 97 is through a terminal rib bead 104 engaging within an annular outwardly opening groove 105 in the plunger and with a clamping ring 107 securing the head in the groove, with an overhanging annular lip flange 108 on the ring overlying the axially outer terminus of the bead and retaining the ring against axial displacement as it serves as a cushioned bumper stop against an end closure disc 109 having a guide bore 110 through which the plunger 97 extends in freely reciprocal relation. Securement of the end closure 109 in a slightly enlarged rabbeted end opening 111 of the housing 87 also sealingly secures a terminal bead rib 112 on the housing-engaging end portion of the sleeve 104 and seated in an annular radially outwardly opening groove 113 in the perimeter of the closure disc, with the bead opposing an axially outwardly facing retaining shoulder 114 at the inner end of the closurereceiving rabbet groove opening 111.

Filling of the buffer unit 85 may be effected while the plunger 97 is partially retracted. Then after the closure plug 91 is secured in place, the plunger is released so that the biasing spring 100 thrusts it through its maximum protracted position. This causes a negative internal pressure within the chamber 102 and the sleeve 104 stretches inwardly and radially under atmospheric air pressure to provide the expanded air chamber 103. When the plunger is stroked inwardly under working conditions, hydraulic fluid displaced by the plunger moves 1nto the reservoir space and the sleeve relaxes to serve as an accumulator, substantially as visualized in FIGURE 6.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

I claim as my invention:

1. A hydraulic buffer comprising:

a tubular housing having opposite end closures and defining a cylindrical working chamber;

metering means of substantially smaller diameter than said chamber and concentric within the chamber projecting from one end closure toward the opposite end closure;

hydraulic fluid within the chamber;

a plunger of substantially smaller diameter than said chamber coactive in metered fluid displacing relation with said metering means and extending from said one end closure;

said opposite end closure having an opening through which said plunger passes in freely reciprocable relation;

a coiled expansible compression spring concentric with said piston having one end thrusting against a surface fixed with relation to said one end closure and its opposite end thrusting against a shoulder on said plunger whereby to bias the plunger normally into protracted relation to said housing and with a portion of the plunger remaining inside of said opposite end closure in the fully protracted position of the plunger;

and combination fluid sealing means and accumulator means comprising a flexible fluid-impervious sleeve about said plunger and spring and having a smaller diameter end and a larger diameter end, said smaller diameter end sealingly secured to said inside portion of the plunger and said larger diameter end sealingly secured to said housing and thereby sealing the chamber against leakage through said opening;

said sleeve comprising a flexible and expansible and contractible accumulator wall in a space within the chamber between the plunger and the housing.

2. A bufler according to claim 1, comprising a flange dlSk seated within said chamber against said one end closure and mounting said metering means, said disk having said fixed surface.

3. A butler according to claim 2, said spring being located in concentric relation about said metering means and said plunger, a tubular guard on said flange disk about said spring and between said spring and said sleeve.

4. A buffer according to claim 2, said spring being located inside said metering means and said plunger.

5. A bulfer according to claim 1, said spring being located in surrounding relation to said metering means and said plunger, and guard means between said spring and said sleeve to maintain the sleeve spaced from the spring.

6. A buffer according to claim 5, said guard means comprising an elongated tube.

7. A hydraulic buffer comprising:

a tubular housing defining a chamber and having closures at its opposite ends;

metering means within said chamber projecting from one of said closures;

hydraulic fluid within that portion of the chamber having the metering means, but only partially filling the housing;

a plunger extending in freely reciprocable inward bufl'ing stroke and outward return stroke relation through the other of said closures and coacting in metered fluid displacing relation with said metering means during said strokes;

a resiliently flexible fluid-impervious sleeve within said chamber about said plunger having one end larger than the other end sealingly secured to said housing and having its opposite end smaller than said one end and sealingly secured to said plunger and isolating a hydraulic fluid-containing reservoir space about said metering means and said plunger from an air space within said chamber opening to atmosphere through said other closure, said sleeve being ret-roverted during one of said strokes of the plunger and during said buifing stroke providing an accumulator for hydraulic fluid displaced by the plunger occupying part of said air space; and

a return spring which at one end thrusts toward said one end closure and at its opposite end thrusts against the plunger for normally biasing the plunger in the outward return stroke direction, said spring being inside said sleeve.

8. A buffer according to claim 7, said sleeve contracting radially inwardly relative to said housing during bufling strokes of the plunger.

9. A buffer according to claim 7, said smaller end of the sleeve having an integral annular bead, said plunger having an annular groove within which said bead is engaged, and a clamping ring securing said bead in said groove.

10. A hydraulic buffer comprising:

a tubular housing defining a chamber and having closures at its opposite ends;

metering means within the housing projecting from one of said closures;

hydraulic fluid within that portion of the chamber having the metering means, but only partially filling the housing;

a plunger extending in freely reciprocable inward bufling stroke and return stroke relation through the other of said closures and coacting in metered fluid displacing relation with said metering means;

a resiliently flexible fluid-impervious sleeve within said chamber about said plunger sealingly secured at one end to said housing and at its opposite end engaging said plunger;

and a clamping ring securing said opposite end of the sleeve to the plunger and serving as a bumper stop engaging said other end closure.

11. A buffer according to claim 10, including a thrust washer engaging a portion of said sleeve contiguous to said opposite end of the sleeve and thrusting such portion of the sleeve toward said clamping ring, and a compression spring thrusting at one end against said thrust washer and at its opposite end toward said one closure.

12. A bufler according to claim 10, said opposite end of the sleeve having an annular bead, said plunger having a groove in which the bead is engaged, said clamping ring having a lip flange engaging against said opposite end of the sleeve to retain the clamping ring against longitudinal displacement upon engagement with said other end closure.

References Cited UNITED STATES PATENTS 1,064,204 6/1913 Furlow. 3,121,479 2/ 1964 Dillen-burger et al. 3,160,910 12/1964 Quinn. 3,229,971 1/ 1966 Stretch et al.

FOREIGN PATENTS 1,004,261 11/1951 France. 1,152,352 9/1957 France.

920,534 11/ 1954 Germany.

21,732 9/ 1912 Great Britain. 792,895 4/ 1958 Great Britain.

GEORGE E. A. HALVOSA, Primary Examiner.

US. Cl. X.R. 

